Internet giant Amazon on Monday opened its plant-packed "The Spheres" buildings in Seattle that it hopes to spark new ideas for employees. The Spheres are the newest addition to Amazon's "urban campus" in Seattle, and are billed as a workplace "more like a tropical rainforest in the clouds than an office." The structures, which look like giant glass and steel balls, house more than 40,000 plants and include features such as treehouse meeting rooms, a river and waterfalls.